[PATCH 0/4] iopoll support for io_uring/nvme passthrough

[Kanchan Joshi]

Hi,

Series enables async polling on io_uring command, and nvme passthrough
(for io-commands) is wired up to leverage that.

512b randread performance (KIOP) below:

QD_batch    block    passthru    passthru-poll   block-poll
1_1          80        81          158            157
8_2         406       470          680            700
16_4        620       656          931            920
128_32      879       1056        1120            1132

Polling is giving the clear win here.
Upstream fio is used for testing.

passthru command line:
fio -iodepth=64 -rw=randread -ioengine=io_uring_cmd -bs=512 -numjobs=1
-runtime=60 -group_reporting -iodepth_batch_submit=16
-iodepth_batch_complete_min=1 -iodepth_batch_complete_max=16
-cmd_type=nvme -hipri=0 -filename=/dev/ng1n1 -name=io_uring_cmd_64

block command line:
fio -direct=1 -iodepth=64 -rw=randread -ioengine=io_uring -bs=512
-numjobs=1 -runtime=60 -group_reporting -iodepth_batch_submit=16
-iodepth_batch_complete_min=1 -iodepth_batch_complete_max=16
-hipri=0 -filename=/dev/nvme1n1 name=io_uring_64

Bit of code  went into non-passthrough path for io_uring (patch 2) but I
do not see that causing any performance regression.
peak-perf test showed 2.3M IOPS with or without this series for
block-io.

io_uring: Running taskset -c 0,12 t/io_uring -b512 -d128 -c32 -s32 -p1
-F1 -B1 -n2  /dev/nvme0n1
submitter=0, tid=3089, file=/dev/nvme0n1, node=-1
submitter=1, tid=3090, file=/dev/nvme0n1, node=-1
polled=1, fixedbufs=1/0, register_files=1, buffered=0, QD=128
Engine=io_uring, sq_ring=128, cq_ring=128
polled=1, fixedbufs=1/0, register_files=1, buffered=0, QD=128
Engine=io_uring, sq_ring=128, cq_ring=128
IOPS=2.31M, BW=1126MiB/s, IOS/call=31/31
IOPS=2.30M, BW=1124MiB/s, IOS/call=32/31
IOPS=2.30M, BW=1123MiB/s, IOS/call=32/32 

Kanchan Joshi (4):
  fs: add file_operations->uring_cmd_iopoll
  io_uring: add iopoll infrastructure for io_uring_cmd
  block: export blk_rq_is_poll
  nvme: wire up async polling for io passthrough commands

 block/blk-mq.c                |  3 +-
 drivers/nvme/host/core.c      |  1 +
 drivers/nvme/host/ioctl.c     | 73 ++++++++++++++++++++++++++++++++---
 drivers/nvme/host/multipath.c |  1 +
 drivers/nvme/host/nvme.h      |  2 +
 include/linux/blk-mq.h        |  1 +
 include/linux/fs.h            |  1 +
 include/linux/io_uring.h      |  8 +++-
 io_uring/io_uring.c           |  6 +++
 io_uring/opdef.c              |  1 +
 io_uring/rw.c                 |  8 +++-
 io_uring/uring_cmd.c          | 11 +++++-
 12 files changed, 105 insertions(+), 11 deletions(-)

-- 
2.25.1